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Household mould thriving

July 10th, 2008

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Even if your home looks clean, chances are good you've got mould, often at levels high enough to trigger allergy and asthma attacks.

That bit of dour news comes courtesy of a new study that also found that mould is frequently in areas most people don't associate with it -- windowsills, for instance.

After surveying 160 homes in seven U.S. cities, Kelly A. Reynolds of the University of Arizona, Tucson, found that 100 per cent of the homes tested positive for mould on some inside surface.

"On average, four sites per house were positive for mould," said Ms. Reynolds, who presented her findings this week at the annual meeting of the American Academy of Allergy, Asthma and Immunology in Denver.

Although 96 per cent of the homeowners in the study knew mould could be a problem, she adds, only 17 per cent felt their home would have a mould problem.

Then came the survey results: 88 per cent of the homes had mould on windowsills; 83 per cent had mould on refrigerator seals (that accordion-like part); 83 per cent had it under the kitchen sink and 82 per cent had it in air vents.

Predictably, the bathroom was also a good breeding ground, though not as good as other areas. Almost half of the shower grouting areas and the walls above the showers showed evidence of mould.

Ms. Reynolds did not measure exact levels of the moulds, but rather did a "presence-absence" test, basically getting a positive or negative result for mould but not how much was there.

Mould releases microscopic fungal spores that, if inhaled, can trigger allergy and asthma symptoms in sensitive people, Ms. Reynolds said. Mould can also worsen or cause sinus infections. High mould levels can also cause symptoms such as coughing and sniffling, which people often mistake for colds or flu, she adds.

The levels of mould needed to trigger an allergy, asthma or sinus problem vary greatly by type of mould and an individual's sensitivity, Ms. Reynolds said.

"The moulds we found were all highly allergenic moulds," she said. Her research was funded by an educational grant from Clorox Co., which makes bleach.

"No standards have been set by any agency" to say at what level mould can cause ill health effects," she adds, noting "some experts say any mould you can smell or see should be eliminated."

Even though the surveyed homes were in various climates, including Dallas, New York, Atlanta, San Francisco, Tampa, Fla., Tucson and Chicago, no substantial geographic differences were found in the levels of mould, Ms. Reynolds added.

One piece of relatively good news from the study: Only 0.2 per cent, or two samples, of the 1,330 taken were found to be Stachybotrys, the so-called "toxic" or "black" mould that can cause bleeding in the lungs of infants.

Another expert, Dr. Jordan S. Josephson, a New York sinus infection expert, is not surprised by the findings.

"I know mould is pretty much ubiquitous," he said. "You can smell it in movies, locker rooms" and other dark, damp places where moulds thrive.

Mould can not only aggravate asthma and allergy, it can also lead to or worsen sinus problems, added Dr. Josephson, director of the New York Nasal and Sinus Center and an attending physician at New York's Lenox Hill Hospital.

"Once you end up with fungal sinusitis, it lingers," he said. "Most people aren't aware that mould causes such problems."

Keeping mould at bay requires vigilance and the proper cleaning solution. Ms. Reynolds recommends cleaning areas with bleach before mould has a chance to build up.